Is it bad to do dumbbell curl and preacher curl with ez bar ?


my workout routine for my biceps are this
•3 sets of preacher curls
•3 sets of standing dumbbell curls
•4 sets of weighted chin-ups with belt




Now I been noticing that my preacher curls are increasing in reps/weight every week.

but i been stuck with ****ING 30 lb's on my dumbbell curl... for the past month.


So... I decided to do dumbbell curls first and I noticed i can do more reps then last time and i came to the conclusion that the preacher curls is what wears down my bicep and prevents me from increasing weight with curls... because im already shot from the preacher curl....




so my question is...


should i get rid of dumbbell curls and do the dumbbell curl forced negativity instead?


or just do dumbbell curls first? and preacher curl 2nd?


but i did this and i did 4 reps of preacher curl . then 6 reps.. then 4 reps.. when the week b4 i was doing 10 reps...


getting pissed off.